This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 19 |
| 3 | 112 |
| 4 | 751 |
| 5 | 5404 |
| 6 | 40573 |
| 7 | 313408 |
| 8 | 2471167 |
| 9 | 19791004 |
| 10 | 160459069 |
| 11 | 1313922064 |
| 12 | 10847561089 |
| 13 | 90174127684 |
| 14 | 754009158019 |
| 15 | 6336733626112 |
| 16 | 53489159252671 |
| 17 | 453258909448636 |
| 18 | 3854034482891725 |
| 19 | 32871004555812112 |
| 20 | 281127047928811201 |
| 21 | 2410285909684370788 |